...FORBES ROBERTSON Abstract Knoop indentation hardness numbers may be obtained on polished mineral grains as small as 10 microns in diameter. This paper gives average Knoop numbers for 127 opaque minerals and quartz. The limits of tests and the average hardness number are plotted on a logarithmic...

...A. A. Giardini Abstract The directional hardness of single crystal silicon has been investigated both by a method of peripheral grinding on oriented thin circular specimens and by Knoop micro-indentations. Grinding hardness has been evaluated in the principal zones [100], [110] and [111]. Knoop...

...Horace Winchell Abstract The Tukon testing machine with a Knoop indenter has useful possibilities in the measurement of hardness of mineral specimens. Not only does the instrument afford numerical hardness values such as argentite = 25, calcite = 100, fluorite = 150, magnetite = 700, corundum...

... linear relationship was obtained when the logarithm of Mohs' hardness number was plotted against the Vickers' microhardness value. This allowed a recomputation of Mohs' numbers which established that the numbers are far from arbitrary and are spaced in a reasonably systematic manner, except possibly...

...D. K. Paul; S. S. Saha Abstract The Knoop indentation hardness number of dolomite (dolostone) increases with increase in Ca and Mg. GeoRef, Copyright 2008, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society...

..., and reported a logarithmic trend of Mohs number with scratch hardness. Experimental techniques for the indentation of brittle materials were further developed in the 20 th century. For example, Knoop et al. (1939) described a pyramidal diamond indenter probe that could be operated at light loads (<10...

... ; Whitney et al. 2007 ) showed hardness values that are different according to the measurement technique used, which is commonly attributed to (1) indenter geometries (Knoop, Vickers, or Berkovich); (2) applied loads; (3) time at the maximum load; and (4) number of indentations. However, in this case, major...

... and dried at 105 ± 5°C. Bulk densities (γ b ) and water imbibition coefficient (IC) were measured on cube-shaped specimens, 3 cm on an edge (Normal 7/81, 1981). The Vickers and Knoop micro-hardness values were determined (40 imprints on each sample with a load of 100 g) by means of a Leitz-Durimet on 30...

... determinations have been supplemented by index of refraction determinations on the glass formed by the fusion of clay specimens. Indentation numbers are obtained with a Wilson “Tukon” hardness tester. Shale fragments are mounted in polyresin in the form of a disc about one inch in diameter and 1 2...

.... 16, entirely repeated on p. 197) compares the Mohs hardness scale and VHN 100 and Knoop hardness scales, when at most a simple plot of Mohs versus VHN hardness would have illustrated the non-linear nature of the Mohs scale. Table C7 (six pages) lists the symmetry symbols for the 32 crystal classes...

... that LP204-1 magnetite grains have a Vickers hardness of 604 ± 19 kg/mm 2 (and a comparable Knoop hardness) whereas 90LP9 magnetite grains have a hardness of 544 ± 27 kg/mm 2 . The Vickers (and Knoop) hardness of 94AK3 was intermediate between those of 90LP9 and LP204-1 at 579 ± 23 kg/mm 2 . We attribute...

... 557 602 Robertson, 1961 Robertson F. 1961 Knoop hardness numbers for 127 opaque minerals Geol. Soc. Am. Bull. 72 621 637 Solari et al., 2004 Solari L.A. Keppie J.D. Ortega-Gutiérrez F. Cameron K.L. López R. 2004 ∼ 990 Ma peak granulitic metamorphism...

... to the independent being, but to all living beings should be common the power of plasmic synthesis, at least to a certain degree. We may consider the glucose sugar as a starting point and some here in its metabolites, e.g ., the ketoacid 3 consider an amination (according to Martius and Knoop ( 1937...

... before ). Note significant loss of intensity at bond angles less than 140°. Microhardness tests of silica showed that both the crack initiation load and the Knoop hardness were constant with time in a dry non-aqueous environment, but decreased with time when exposed to ambient or water conditions...

... of rupture energy 14205:2003 Determination of Knoop hardness D5873-05 Determination of rock hardness by rebound hammer method 14579:2004 Determination of sound speed propagation 14580:2005 Determination of static elastic modulus D7012-10 STM for compressive strength and elastic...

... imposes constraints on the attainable pressures in high-pressure apparatus. The Knoop hardness of tungsten carbide is generally in the range of 10–15 GPa, while that of diamond of gem quality is ~100 GPa. Thus the pressures available in a Bridgmann-type apparatus were limited to ~20 GPa, while pressures...

... but wider orthogonal lines recorded deeper sections with the same number of sensors. Repositioning of wireless geophones was done during casing/cementing operations. In addition, several lines were deployed in a saw-tooth-like pattern to test additional options for better noise separation during...

... as catalyser. Glucose is the central substance of biochemistry after J. Mark. 107 It is the starting point for the formation of organic acids (Kluyver), of fats ( Haehn and Kintoff, 1923 and 1924), of protein (Knoop, Oesterlin, Chibnall), 108 and of the great number of other classes of substances...

... bodies in the limestone with sulfide mineralized veinlets in the hanging-wall shales and sandstones. In many areas these shales are metamorphosed to hard, compact pyritic hornfels. Mantos consist of massive fine- to coarse-grained pyrite, pyrrhotite, galena, and sphalerite, with minor chalcopyrite...

.... Microhardness measurements have been performed by Léger et al. (1996) on stishovite polycrystals synthesized at 20 GPa and 1100°C. The high shear modulus (220 GPa) and Knoop hardness (33 GPa) exhibited by stishovite at ambient pressure have classified it as a “superhard” material (immediately following...